1. Field of the Invention
The invention relates generally to optical fibers. More specifically, the invention relates to an apparatus and method for securing an optical fiber preform in a spindle to reduce vibration in a resulting twisted fiber.
2. Discussion of the Related Art
In the fabrication of optical fiber preforms, it is difficult to keep a preform perfectly straight and uniform. In conventional spinning of preforms during fiber draw, resulting non-uniformities permit a preform to wobble when spun. These induced wobbles, known as run-out, may cause a fiber drawn from the preform to oscillate to a point of breaking at high spin rates.
It is desirable to produce fiber that is drawn at high draw speeds. Further, fiber may be twisted as it is being drawn from the preform. Unfortunately, related art techniques that employ gulp and wobble wheels to impart a twist on drawn fiber are limited in the twist rate possible. Other mechanical wheels can increase twist rate but leave a mechanical twist in the fiber that renders the fiber difficult to handle and can damage the fiber's external coating.
Preform spinning overcomes these limitations while providing high twist rates with little mechanical twist left in the optical fiber without imparting damage to the coating. As preforms become larger and more complex (e.g., the production of multi-core fibers), holding and accurately spinning a preform while maintaining tight diameter control and twist rates becomes a problem.
In conventional methods of manufacturing twisted optical fiber from a spinning preform, it is important to have the center of rotation of the preform in line with the optical fiber line. Any run-out of the preform may induce a vibration in the twisted optical fiber when drawn. Further, a non-tightly-secured preform may also induce vibrations in the twisted optical fiber. Variations in preform dimensions may also contribute to excessive run-out.
Thus, a need remains in the art for a method of manufacturing an optical fiber that permits spinning of less than perfect optical fiber preforms of various diameters and that securely holds a preform while reducing induced vibration in both the resulting drawn fiber and in control equipment.